Highly Efficient Synthesis of Cephalotaxine by Two Palladium‐Catalyzed Cyclizations

Abstract

Interesting for cancer therapy: The unique pentacyclic alkaloid cephalotaxine is the parent compound of the strongly cytotoxic harringtonines, which are isolable from the study-east Asian yewtree. Now the cephalotaxine precursor 2 has been synthesized highly efficiently and selectively in two steps from the readily accessible amine 1 through an intramolecular Pd-catalyzed allylic amination to form the spirocycle (85% yield) and subsequent Heck reaction to construct the seven-membered ring (80% yield).